At the end of Tuesday’s episode, Jack (Milo Ventimiglia) confessed to his wife, Rebecca (Mandy Moore), that he had been battling alcoholism for “a while,” keeping it hidden from his loved ones. The scene that got everyone talking, though, took place right after Rebecca vowed they would “fix” his drinking “together,” when the show flash-forwarded to the day of Jack’s death, revealing a devastated Rebecca in the station wagon (with Jack’s prized possessions in a bag) and the family home completely destroyed in a fire. How Jack died, viewers now know, is connected to a house fire -- though the how, why and what remain unanswered for now.

“We’d planned this for six months,” Fogelman tells ET of the final scene, which was filmed just a week and a half ago to avoid spoilers and leaks. “This scene that you’re referring to at the end of the episode was part of my initial pitch a year and a half ago to NBC when I gave them the script for the pilot. I said, ‘Here’s how he dies. Here’s when we’re going to reveal it. Here are the pieces we’re showing in the second season.’ We just executed a plan. We have a very talented actress, who’s able to do a very high-water [scene]. Keeping it a secret was very hard.”

The secrecy surrounding the revelation was unlike anything the show has dealt with before and Fogelman admitted it was stressful keeping a piece of intel as sought after as Jack’s death under lock and key until the episode aired.

“It’s been up on boards in our [writers’] room and talked about openly for a year and a half. But we were very careful and I often came off like somebody who was too uptight worrying about it,” Fogelman said. “Our fans feel so deeply with this show and whether or not that’s how they want Jack to die or when they want the information, I felt a responsibility [to] let them learn it in real time. If they’re fans of the show watching it on DVR or live, I don’t want them reading about it four months in advance or in an interview.”

Fogelman praised Moore’s heart-wrenching performance in that last moment, when Rebecca -- in pure shock over her husband’s death -- drove to the charred remains of the Pearson home and broke down sobbing. Moore aced the scene on her first take.

“We did three takes [total], because it felt weird to drive Mandy out for three hours and make her only do one take. I don’t often go to set, but I went to set [that day] because I wanted to make sure the house looked right. Mandy did one take and it was over,” Fogelman recalled.

Much of the focus has been placed squarely on Jack, in part due to the mysterious circumstances surrounding his untimely death, and the nostalgic effect his character holds over his family in the present-day storylines. Fogelman has high hopes, though, that Moore’s work as Rebecca this season will get a prime spotlight.

“Personally for me, I think Mandy has been underrated with what she’s doing on the show. This season is her basically stepping up and announcing, ‘I’m not playing right now,’” he said, before referencing her breakdown as an example. “That seems like a very simple thing -- to explode in raw, powerful grief in a wide shot -- but it’s not an easy thing to do. To me, it’s stunning.”

When it comes to unraveling the story behind Jack’s secret battle with his alcoholism, which, as it’s revealed in the premiere, is far more serious than previously thought, next week’s episode will begin to explore why and how things got so bad for the Pearson patriarch.

“The next episode picks up literally with Jack having gotten into the car with Rebecca to go home and we explore this through Jack’s drinking in different timelines -- including mustache Milo, when we didn’t think he had a drinking problem [and] what he was battling,” Fogelman said. “If you remember, in the second episode of our series, Rebecca sat him down and said the drinking needs to stop. We’re going to explore what happened after that time period, what happened in this time period. It’s going to be very much about the underbelly of this guy, who still is the fantastic, most perfect husband in the world. [But] like all of us, [he] has his demons and that’s very much what his story is this year.”

Fogelman assures that there is “a plan” in place when it comes to how regularly clues to the story of Jack’s death and that fateful day will be parceled out.

“It’s carefully constructed. It’s, frankly, always the plan we had,” he said, echoing that “everything you need to know” about Jack’s demise comes “in the course” of season two. “The clues will be doled out appropriately. It’s not going to happen next week and it’s not going to happen in the season finale.” Asked if it could come midway through the sophomore run, Fogelman was coy: “There are a lot of clues we have to tell.”

“Now that people have a little bit of information, hopefully it’ll lessen [the load],” he later adds, pointing to clues like Kate’s dog, Randall’s girlfriend and Kevin’s broken leg that “we’ll be building” the mystery toward. “We’re not intending for people not to talk about it or focus on it. Clearly, it’s the end of the first episode and it is the hinge on which this family swings. Hopefully, people have been satiated enough that it gives enough that we get to where we need to be.”

The ticking clock on Jack’s mortality, from the moment he steps into the car with Rebecca to the day of his death, isn’t as long as one would presume. Rebecca says in voiceover, assuring a defeated Jack, “A few months from now, everything will be back to normal.” Fogelman all but confirmed that the voiceover is to be taken as a tangible timeframe for when Jack’s life ends. “We’ve done everything by choice, so there was nothing accidental,” he hinted of that specific moment.

In the present day, Beth and Randall’s adoption journey takes a slight detour, with the couple agreeing to look into potentially adopting an older child, a decision that comes into play in full force in the third episode.

“There is an exciting young actor joining our show -- actor or actress, I won’t give anything away about the gender,” Fogelman teased. “It’s an exciting, interesting storyline with an exceptional young actor who holds his or her own opposite Sterling [K. Brown] and Susan [Kelechi Watson], which is not an easy task. It’s going to be a really interesting piece of television for a while. It explores something that we don’t always see on TV.”

As for how the season two premiere (and beyond) is received by viewers, Fogelman praised Ventimiglia and Moore for bringing their A game.

“I hope people really liked it. I hope people enjoyed it,” he said. “I think we’ve made a very special piece of television that’s going to be with people for a while, and a large part of that is because of what Mandy and Milo do in that final scene and then what Mandy does in that car. It’s powerful.”